• 한국융합학회논문지
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• 제9권11호
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• pp.29-35
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• 2018

본 연구는 준 마이크로파 대역에서 슬롯(slot) 결합 커패시터 공진기를 이용하여 Nacl 수용액의 농도변화를 감지할 수 있는 고감도 센서를 제안하였다. 센서에 적용되는 공진기는 마이크로스트립 선로의 접지 면을 활용하여 유도성 슬롯(inductive slot)과 연결된 평행판 커패시터로 구성된다. 농도변화에 따른 유전특성 측정데이터를 기반으로, 농도변화가 확연히 드러나는 UHF 대역에서 공진주파수가 정해졌으며, 평행판 커패시터 내에 Nacl 수용액이 삽입된다. 시뮬레이션을 토대로 제안된 공진기를 설계하여 제작하였다. 농도 변화를 0 mg/dl에서 400 mg/dl까지 100 mg/dl 단계로 실험하였고, 전송 산란계수($S_{21}$)가 측정되었다. 실험결과 각 단계별 최소 1.8 dB($S_{21}$)의 변화를 얻음으로써 Nacl 수용액에서 농도검출 센서에 적용가능함을 입증하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.185-190
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• 1998

Corrosion of steel reinforcement is the most significant factor of deterioration in reinforced concrete structures. Chloride ion is considered one of the most common culprits on the corrosion of steels in concrete. The main objective of this study is understanding behavior of chloride ion in hardened cement pastes at different stages of curing. Cement pastes with water-cement ratio of 0.5 are allowed to hydrate in sealed containers for 28, 70, 180 days. And than pore solution is expressed. It was found that the $Cl^-$ concentrations in pore solution is decreased with increasing curing time in all Nacl addition level, the $OH^-$ concentrations is increased to 70 days but decrease at 180 days in all Nacl addition level. The $Cl^-$/$OH^-$ in pore solution is increased with increasing curing time in all Nacl addition level, however $Cl^-$/$OH^-$ of maximum Nacl addition level(Nacl 0.54% by weight of cement) is under the onset of depassivation level 0.3.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.585-589
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• 2007

Gas hydrate is a special kind of inclusion compound that can be formed by capturing gas molecules to water lattice in high pressure and low temperature conditions. When referred to standard conditions, $1m^3$ solid hydrates contain up to $172Nm^3$ of methane gas, depending on the pressure and temperature of production, Such large volumes make natural gas hydrates can be used to store and transport natural gas. In this study, three-phase equilibrium conditions for forming methane hydrate were theoretically obtained in aqueous single electrolyte solution containing 3wt% Nacl. The results show that Nacl acts as a inhibitor, but help gases such as ethan, propane, i-butane, and n-butane reduce the hydrate formation pressure at the same temperature.

• 분석과학
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• 제11권2호
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• pp.125-129
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• 1998

치과재료로서 금합금을 대체하기 위하여 Pd-In-Ag 합금을 설계해서 인공체액과 0.9% Nacl용액 링거용액에서 변색실험을 행하였다. 인공체액과 0.9% Nacl 용액에서는 은의 함량증가에 대하여 높은 변색을 보였으나 링거용액에서는 은의 함량 증가에 따른 변색 영향이 관찰되지 않았다. 합금개발을 위하여 Pd와 In, Ag의 변색 영향을 조사하였고 새로운 합금의 설계가 시도되었다.

• 한국표면공학회지
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• 제26권5호
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• pp.271-279
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• 1993

Experiments on electorchemical etching of aluminum foils with high cubic textures were carried out in this study. Etching behaviours and pit shapes with respect to various conditions of eletrochemical etching were in-vestigated. When HCl and NaCl solutions were used as electrolytes, the highest capacitanes were observed in solutions of 1MHCl and 5M NaCl. It was foundd that capacitance was improved by addition of H2SO4 to HCl so-lution which is considered to be due to the suppression of oxide film formation on the aluminum surface. The homogeneous distribution of each pits obtained in the HCl solution, while the degree of weight loss was lowest in the Nacl solution. The best etching properties in 1M HCl solution were obtained at the etching condi-tions of 0.15 A/$\textrm{cm}^2$, 150sec and$ 90^{\circ}C$.

• 한국조리학회지
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• 제18권1호
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• pp.40-53
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• 2012

$90^{\circ}C$의 물, 0.5% NaCl 용액, 1.0% Nacl 용액, $400^{\circ}C$ 과열수증기 등을 사용하여 가열 조리한 오이, 애호박, 당근, 무, 양파 등의 채소류의 품질변화를 살펴보았다. 가열에 의한 채소류의 pH는 증가하는 경향을 보였다. 가열조리한 채소류의 색 변화를 Hunter 색차계를 사용하여 L값(밝기), a값(적색도), b값(황색도)을 측정한 결과 $400^{\circ}C$ 과열수증기로 30초간 처리한 채소류의 색변화가 $90^{\circ}C$의 물, 0.5% NaCl 용액, 1.0% Nacl 용액에서 처리한 것보다 L값(밝기), a값(적색도), b값(황색도)등의 변화가 적어 변색이 적게 일어난 결과를 나타내었다. 채소류에 존재하는 오염 미생물은 $400^{\circ}C$ 과열수증기로 30초간 처리한 채소류에서 매우 효과적으로 생육이 억제되었다. 가열조리에 의한 비타민C의 함량 변화는 조리방법과 채소류의 종류에 따라 비타민C 잔존율에 차이가 있었다. 고온의 과열수증기를 이용한 단시간 조리법은 $900^{\circ}C$의 물, 0.5% NaCl 용액, 1.0% NaCl 용액 등에서 처리한 일반 가열조리법에 비하여 pH, 색, 세포연화, 비타민C 감소율 등의 변화가 적게 나타났다. 본 논문의 연구 자료는 앞으로 진행될 가정 대용식(HMR, Home Meal Replacement)의 개발에 이용될 것이다.

• 한국해양공학회지
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• 제6권2호
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• pp.85-93
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• 1992

The only hardness of 2nd phase of martensite in dual phase steel which was composed of the martensite and ferrite was changed. Fatigue test was conducted by cantilever type of self-made rotated bending fatigue testing machine. The corrosion fatigue fracture behaviors of dual phase steel were investigated in 3% NaCl solution at $N_f$ = $1.5\times$$10^5$ $N_f$=1.0 $\times$ $10^6$ cycles. The fatigue strength was increased with increasing the hardness of 2nd phase. The size and number of corrsion pits were influenced by the 2nd phase hardness and pits remain constant in size just after they were transited into cracks. The life of crack initiation was effected by stress level. The shape of relation of $\Delta$K and da/dn has smaller scattering in it in 3% NaCl solution than that in air. The higher the 2nd phase hardness is, the higher the corrosion fatigue life becomes. Corrosion fatigue fracture behavior was effected by mechanics in case of $N_f$=1.5$\times$10$^5$$N_f$=1.5$\times$10$^6$ cycles.

• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.527-534
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• 1997

Freezing of an aqueous sodium cWoride solution (Nacl- H20) saturating a packed bed with ini¬tial salt concentrations of 5, 10, 15(k by weight is investigated experimentally in a rectangular cav¬ity. The system was cooled from the top, bottom and a vertical side wall. For the freezing experi¬ments from below, there was little effect of the initial salt concentration throughout the freezing process, and the global freezing rate was not affected by the initial salt concentration. For the freezing from above, the size of the mush region decreased and the mushlliquid interface became flatter as the initial liquid concentration is decreased. For the freezing from vertical side wall, reheating of the mixture was intensified with an increase in the initial salt concentration. For Ci= 5%, supercooling was observed only at the early times of freezing process, but for Ci= 15% small supercooling was observed throughout the freezing process.

• 한국주조공학회지
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• 제25권3호
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• pp.134-141
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• 2005

To overcome the undesirable deformation, peeling off and geometrical restrictions which were mainly caused by differences in thermal expansion coefficients during the cladding of aluminum strip and stainless strip, new processing method based on vacuum die casting is designed and implemented in fabricating Al/Fe-17wt%Cr steel(stainless steel). To increase cast-bonding ability, the surface of Fe-17wt%Cr steel is electrochemically etched to have optimum pit size and density. The optimum conditions to generate best pit are as follows: Solution: 1 M $Fecl_{3}$+1 M Nacl, Addition: $CuCl_{2}+HCl$, Current density: 80 $mA/cm^{2}$, Total current: 400 $coulomb/cm^{2}$, AC frequency :60 Hz.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.254-254
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• 2012

The purposed of this work was to determine surface charateristics of anodized Ti-30Nb-xTa alloys with Ta content. Samples were prepared by arc melting, followed by followed by homogenization for 12 hr at $1000^{\circ}C$ in argon atmosphere. The electrolyte for anodization treatment was prepared by mixing 465ml $H_2O$ with 35M $H_3PO_4$ and anodized at 180V to 220V. The microstructures of the alloys were examined by X-ray diffractometer (XRD) and optical microscopy (OM). Surface characteristics of anodized Ti-30Nb-xTa alloys was investigated by potentiodynamic test and potentiostatic in 0.9% Nacl solution at $36.5{\pm}1^{\circ}C$. It was observed that the changed ${\alpha}$ phase to ${\beta}$ phase with Ta content.